Recordings on a magnetic disk can be performed either longitudinally or perpendicularly. In longitudinal recording, information is stored within or parallel to the plane of the magnetic disk. In perpendicular recording, information is stored perpendicular to the plane. Longitudinal recording products have been commercially available for some time; new perpendicular recording products are being developed because of the potential for much higher storage capacity compared to longitudinal recording.
Perpendicular recording has some issues associated with it that were not previously encountered or were not as noticeable with longitudinal recording; baseline wander is one such issue. Although there are techniques that address baseline wander, they may be unattractive due to a variety of reasons. For example, some existing techniques add noise, have a slower response time than the baseline wander, and/or discard some of the signal, thus reducing the amount of signal used in error correction decoding. New techniques for dealing with baseline wander that overcome some or all of these drawbacks would be attractive.